Effect of heat treatment on microstructures and properties of Zr-rich α TiZrAl alloy

The microstructures and properties of two kinds of zirconium-enriched alpha alloys (Ti 60 Zr 40 ) 97 Al 3 (mass fraction/degrees 0 ,the same below) ) and (Ti 50 Zr 50 ) 97 Al 3 via different heat treatments were investigated and analyzed based on optical microscope (OM ) observation, , differential scanning calorimetric (DSC ) measurement, , X-ray diffraction (XRD ) measurement, , scanning electron microscope (SEM ) observation and tensile tests at room temperature. The results show that after 850 degrees C/40 min annealing, , microstructures consisting of basket-weave alpha phase and a small amount of reticular beta phase are formed in the alloys. After 850 degrees C/40 min quenching, , the acicular alpha' martensite phase is formed. After 850 degrees C/40 min quenching and then 600 degrees C/4 h aging, , a large part of alpha' martensite phase converts into alpha phase, , and the microstructures of the alloys consist of alpha and alpha' remain phases. The yield strength of the T40Z3A alloy can reach 1100 MPa, , with a favourable tensile elongation of 7 degrees 0. The T50Z3A alloy exhibits higher strength but lower ductility than those of the T50Z3A alloy. Due to the higher content of Zr element, , the T50Z3A alloy has more reticular beta phase after annealing and more remaining alpha' martensite phase after quenching and aging, , which results in higher strength and lower ductility.